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Effect of level of inclusion of Bioplex® Copper or CuSO4 on the performance and indicators of copper status in dairy cows.

Experiment to determine the effect of inclusion of Bioplex® Cu or CuSO4 on the performance and indicators of Cu status in dairy cows.

Year of Publication2010

It is well established that copper (Cu) is an essential mineral required to maintain the health and performance of dairy cows. Cattle diets have traditionally been supplemented with inorganic sources such as CuSO4, often at levels well in excess of dietary requirements. It is claimed that organically-bound minerals are able to resist interactions before and at the absorption site in the small intestine, which may result in a lower dietary requirement. An experiment was therefore conducted to determine the effect of inclusion of Bioplex® Cu or CuSO4 on the performance and indicators of Cu status in dairy cows. Fifty six Holstein-Friesian dairy cows (20 primaparous and 36 multiparous) were randomly allocated to one of four dietary treatments: either no supplementary Cu (B-0), Bioplex® Cu added at 5 (B-5) or 10 (B-10) mg Cu/kg DM or CuSO4 added at 10 mg Cu/kg DM (C-10). All cows received the same basal total ration that contained (kg/kg DM) 0.57 forage, of which proportionally 0.67 was maize silage and 0.33 first cut grass silage. Background dietary Cu concentrations were 5.7mg/kg DM. Milk yield and intake were recorded daily and milk samples taken weekly for subsequent analysis of fat and protein. Blood samples were collected via jugular venipuncture during weeks 0, 4, 8 and 12 of the study and liver biopsy samples were collected from 8 cows per treatment during weeks 0 and 12. Body condition score and liveweight were recorded weekly. Animals remained on study for 12 weeks. There was no effect (P&gt;0.05) of dietary treatment on DM intake or milk yield, which averaged 22.2 and 36.0 kg/d respectively. Similarly, there was no effect (P&gt;0.05) of treatment on milk composition, liveweight or body condition score. Indicators of Cu status are presented in Table 1. Plasma Cu concentrations were similar in cows receiving any of the dietary treatments, averaging 12.7mmol/l. In contrast there was a trend (P=0.087) for plasma ceruloplasmin concentrations to be lowest in cows fed C-10, whilst the plasma ceruloplasmin:Cu ratio was lower (P&lt;0.05) in cows fed C-10 than B-0 or B-5. Pre-study liver Cu concentrations (mg/kg DM) were higher (P&lt;0.05) in cows fed B-0 than B-10, but there was no difference (P&gt;0.05) at the end of the study period. As a consequence, net liver Cu balance was negative in cows fed no supplementary Cu or CuSO4, but positive in animals fed either of the Bioplex® treatments. It is concluded that level and form of dietary Cu had no effect on performance parameters, but there was a trend for cows fed Bioplex® Cu to be in positive Cu balance, although further studies are required to support this finding.